Simultaneous color television optical system



Sept. l29, 1953 A. c. scHREDE-R -E-r AL 2,653,993

SIMULTANEoUs coLoR TELEVISION OPTICAL SYSTEM Filed April 29, 1948 2 sheets-sheet 1 Sept. 29, 1953 A. C. SCHROEDER ET AL SIMULTANEOUS COLOR TELEVISION OPTICAL SYSTEM Filed April 29, 1948 2 Sheets-Sheet 2 Patented Sept. 29, 1953 SIMULTANEOUS COLOR TELEVISION OPTICAL SYSTEM Alfred C. Schroeder, Feasterville, Pa., and George C. Sziklai, Princeton, N. J., assignors to Radio Corporation of America, a corporation of Dela- Ware Application April 29, 1948, Serial No. 23,914

(Cl. P18-5.4)

15 Claims.

This invention relates to optics, and more particularly to the division of color images into selected color components.

Various proposals have been suggested for dividing a color image into its selected color components or primaries. One such arrangement employs partially silvered mirrors in connection with component color or primary color filters. Another suggestion employs dichroic mirrors.

According to the present invention, component color separation is accomplished electronically, An optical color image is transformed into an electronic image. The electronic image is transerred in toto to intercept an electrode arrangement which transmits electrons traveling above a predetermined velocity and renects electrons traveling at a velocity lower than the predetermined velocity. The present invention is based ior its operation on the Einstein equation of photoelectric phenomena, which states that the initial kinetic energy in a photoelectron is a linear function of the frequency of the liberating radiation.

A primary object of this invention is to provide an improved optical system for dividing a color image into selected component or primary colored images.

Another object of this invention is to provide an improved color television system.

Still another object of this invention is to provide for an improved simultaneous type color television camera.

Other and incidental objects of the invention will be apparent to those skilled in the art from a reading of the following specication and an inspection of the accompanying drawing in which like numerals represent similar elements and in which:

Figure 1 illustrates schematically one form of this invention;

Figure 2 also illustrates schematically another form of this invention;

Figure 3 illustrates graphically the operation of certain forms of this invention;

Figure 4 illustrates schematically still another form of this invention; and

Figure 5 illustrates this invention employed in connection with a simultaneous type color television system.

Turning now in more detail to Figure 1, there is illustrated an evacuated envelope I which contains a photo cathode 3, upon which there 1s focused an image. The photo cathode 3 establishes adjacent thereto, by reason of photoelectric emission, an electron image.

An electrostatic lens including ring 5 is positoned to cause the electrons from the electron image adjacent photo cathode 3 to move to the right toward plate 1 which, in connection with the associated screen electrode 9, causes the electrons flowing from photo cathode 3 to be reflected downward to a target electrode II. Although an electrostatic type lens 5 is shown, an electromagnet lens arrangement may be provided without departing from the spirit of this invention.

The combination of electrodes 1 and 9 operates as an electronic mirror because of the potentials applied thereto. Electrons owing from the photo cathode 3 will be repelled by the relatively negative potential of electrode 1 and due to its sloping position will be reflected downward. The screen electrode 9 is positioned in front of the electrode 1 in order to prevent a disguration of the electrical iield within the member I3, and hence prevent image distortion. It will be seen that the potential of the screen 9 is the same as the potential of the member I3.

Turning now to Figure 2, there is illustrated still another form of this invention involving in an envelope I a photo cathode 3 and its associated electrostatic lens 5.

The form oi the invention illustrated in Figure 2 differs from the form of the invention shown in Figure 1 in that the solid plate 1 of Figure 1 is omitted and replaced with a screen electrode I5.

By reason of the difference in velocity of the electron flow coming from cathode 3, not all of the electrons will be reflected downward by screen I5 as in the case of the plate 1 of Figure 1, but some of the electrons will continue through the screen I5 to fall upon the target electrode I1.

Member I9, together with screen 20, is charged at a positive potential such as that applied to member I3. It follows that if the electrons are traveling at a relatively high rate, they will proceed directly through screen I5 to fall upon target electrode I1, while if they are traveling at a slower rate, they will be reected by screen I5 to fall upon target electrode I I.

The operation of this invention in connection with the division of natural color images into their selected or primary components may perhaps best be understood by a brief reference to electronic theory.

According to the Einstein law of photo emission, electrons leave a photoelectric suriace with an initial velocity proportional to the frequency of the impinging radiation.

In Eins-teins equation of photoelectric phenomena, the initial kinetic energy of a photo electron is a linear function of the frequency of the liberating radiation according to the relation of tion, and qb is the work function. rlhe kinetic The flying spot is divided and reflected to the target electrodes 53, 55 and 51 by the mirrors 65 and 6l, together with the partially silvered mirrors 53 and ll.

The blue image representative signal which is obtained from terminal 53 is applied to amplifier "i3, and the blue signal indicated in the output circuit is obtained directly therefrom.

The green and blue image representative signal obtained from control electrode El is applied to the amplifier l5. The green image representative signal is obtained from the combination of the green and blue image representative signal applied to amplifier 'i5 by subtracting through variable inverting amplifier 11 the proper amount of blue signal.

The red, green and blue image representative signal obtained from terminal 53 is applied to amplifier i9. The red representative signal is obtained by subtracting the green and blue image representative signal through variable inverting amplifiers and 83.

It will therefore be seen that a simultaneous type television signal is obtained.

One important feature of this invention is its employment of a single raster in the development of several selected component color image representative signal trains. This permits accurate registration and results in an improved simultaneous type color television signal.

Having thus described the invention, what is claimed is:

l. An apparatus for dividing optical images into selected component color images comprising means for producing electron images of said optical images, a plurality of electron image targets, electron image focus means for simultaneously transferring all parts of said electron images by electron flow from said electron producing means to at least one of said targets in image focus, the threshold velocity of the electrons in said iiow dependent upon the corresponding electron image area color representative characteristics, and means for selectively reflecting the electrons of said electron oW in accordance With their velocity.

2. Apparatus for dividing optical images into selected component color images comprising means for producing electron images of said optical images, a plurality of electron image targets, electron image focus means for simultaneously transferring all parts of said electron images by electron flow from said electron producing means to at least one of said targets in image focus, the threshold velocity of the electrons in said now dependent upon the corresponding electron image areav color representative characteristics, means for selectively reiiecting the electrons of said electron flow whose velocity is below a predetermined amount, and means for converting each of the divided portions of the electron flow into electron images.

3. Apparatus for converting optical images into a plurality of independent signal trains, each signal train representative of a selected component color portion of said optical images comprising in combination, means for producing electron images of said optical images, a plurality of electron image targets, electron image focus means for simultaneously transferring all parts of said electron images by electron flow from said electron image producing means to at least one of said image targets in image focus, means for dividing said electron fiow in accordance with the velocity of its electrons, means for converting each of the divided portions of the electron flow into selected component color representative signal trains, and means for balancing out that portion of the signal obtained from any one divided portion of said electron oW which is equal to the signal obtained from the next adjacent divided portion of the stream having the next greater velocity.

d. Apparatus for converting optical images into a plurality of independent signal trains, each signal train representative of a selected component color portion of said optical images comprising the combination of means for producing electron images of said optical images, a plurality of electron image targets, electron image focus means for simultaneously transferring said electron images in toto by electron flow from said electron image producing means to at least one of said targets in image focus, the threshold velocity of the electrons in said flow dependentupon the corresponding electron image area color representative characteristics, means for reecting said electron flow in accordance with the velocity of its electrons, means for converting each of thev divided portions of the electron flow into selected component color representative signal trains, and

means for electrically balancing out that portion. of the signal obtained from any one divided por-- tion of said electron flow which is equal to the.y signal obtained from the next adjacent divided; portion of the stream having the next greater` velocity.

5. Apparatus for converting optical images; into a plurality of independent signal trains,I each signal train representative of a selected component color portion of said optical images comprising in combination, means for producing electron images of said optical images, means for simultaneously transferring the complete electron images by electron flow, the threshold velocity of the electrons in said flow dependent upon the corresponding electron image area color representative characteristics, an electronic mirror located at one position along said flow for selectively reiiecting the electrons of said flow Whose velocity is below a first predetermined amount, a second electronic mirror positioned at another position along said flow for selectively reiiecting the electrons of said flow Whose velocity is below a second predetermined amount, said second predetermined amount vbeing greater than said first predetermined amount, means for converting each of the divided portions of the electron flow into selected component color representative signal trains, and means for electrically balancing out that portion of the signal obtained from any one divided portion of said electron now which is equal to the signal obtained from the next adjacent divided portion of the stream having the next greater velocity. p

6. An apparatus for dividing optical images into selected component color images comprising in combination means for producing electron images of said optical images, an electron image target, an electronic lens for simultaneously transferring all parts of said electron images by electron flow, and electronic mirror means for reflecting the electrons of said electron now to said electron image target in image focus in accordance Withr their velocity.

7. An apparatus for dividing optical images into selected component color images comprising in combination a photo cathode for 'producing electron images of said optical images, an electron image target, an electronic lens for simultaneously transferring all parts of said electron images by electron 119W. the threshold velocity 0i the electrons in Seid. .119W dependent upon the Corresponding electron .image area c0101' representative characteristics, and electronic mirror means Vfor selectively reflecting the electrons of said electron flow whose velocity is below a predetermined amount to said electron image target in image focus.

8. An apparatus for dividing optical images into selected component color images comprising in combination a photo cathode for producing electron images of said optical images, an electron image target, an electronic lens for simultaneously transferring all parts of said electron images by electron flow, the threshold velocity of the electrons in said flow dependent upon the corresponding electron image area color representative characteristics, and a combination of parallel electrodes having predetermined potentials applied thereto for selectiveiy reiiecting to said electron image target the electrons of said electron iiow whose velocity is below a predetermined amount.

9. An apparatus for dividing optical images into selected component color images comprising in combination a photo cathode for producing electron images ofsaid optical images, an electron image target, an electronic lens for simultaneously transferring all parts of said electron images by electron flow, the threshold velocity of the electrons in said flow dependent upon the corresponding electron image area color representative characteristics, and a combination of parallel screen electrodes for selectively reflecting the electrons of said election flow whose velocity is below a predetermined amount of said electron image target.

10. An apparatus for dividing optical images into selected component color images comprising in combination a photo cathode for producing electron images of said optical images, a plurality of electron image target electrodes, an electronic lens for simultaneously transferring all parts of said electron images by electron ow, the threshold velocity of the electrons in said flow dependent upon the corresponding electron image area color representative characteristics, and a combination ofj parallel screen electrodes for selectively reflecting the electrons of said electron ilow whose velocity is below a predetermined amount to intercept each of said electron image target electrodes,

11. An apparatus for dividing optical images into selected component color images comprising in combination a photo cathode for producing electron images of said optica-l images, an electronic lens for simultaneously transferring all parts of said electron images by electron fiow, the threshold velocity of the electron in said iiow dependent upon the corresponding electron image area color representative characteristics, and a combination of three parallel screen electrodes having a first potential applied to the outer two of said screen electrodes and having a second potential applied t the inner of said screen, electrodes and selectively reiiecting the electrons of said electron now whose velocity is below a predetermined amount.

12. An apparatus for dividing optical images into selected component color images comprising in combination a photo cathode for producing electron images of said optical images, an electronic lens for simultaneously transferring all parts of said electron images by electron flow, the threshold velocity of the electrons in said flow dependent upon the corresponding electron image area color representative characteristics, and a combination of three parallel screen electrodes having a potential equal to the surrounding space applied to the outer two of said screen electrodes, said combination of electrodes having a potential slightly below the potential of said photo cathode applied to the inner of said screen electrodes, selectively reflecting the electrons of said electron ilow Whose velocity is below a predetermined amount.

13. An apparatus for dividing optical images into selected component color images comprising in combination a photo cathode for producing electron images of said optical images, a plurality of electron image target electrodes, an electronic lens for simultaneously transferring all parts of said electron images by electron flow, the threshold velocity of the electrons in said flow dependent upon the corresponding electron image area color representative characteristics, and a combination of a first set of three parallel screen electrodes positioned in said flow and having a first potential applied to the outer two of said screen electrodes and having a second potential applied to the inner of said screen electrodes, and a combination of a second set of three parallel screen electrodes positioned in said flow and having a third potential applied to the outer two of said screen electrodes of said second set and having a fourth potential applied to the inner screen electrode of said second set.

14, An electronic device consisting of an electron picture image detail emitting surface, an electronic lens system arranged to simultaneously transfer said image detail, an electronic mirror consisting of a screen having a potential substantially equal to the surrounding field, a flat electrode behind said screen in close proximity thereto and charged negatively with respect to the emitting surface, and one or more electron image targets in which the said electron mirror is tilted with respect to the emitting surface.

l5. An electron device consisting of a complete electron image emitting surface, a plurality of electron image targets, an electron lens system positioned to maintain the detail of said image and to simultaneously transfer all parts of said electron image by electron flow, means for selectively reflecting only the electrons of said elec.. tron flow whose velocity is below a predetermined amount, and means for converting each of the divided portions of the electron flow into independent electron images on said image targets.

ALFRED C. SCHROEDER.

GEORGE C. SZIKLAI. References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,126.286 Schlesinger Aug. 9, 1938 2,156,915 Knoll May 2, 1939 2,163,787 Henneberg et al. June 27, 1939 2,243,102 Klemperer May 27, 1941 2,253,292 Goldsmith Aug. 19, 1941 2,294,820 Wilson Sept. 1, 1942 2,332,876 Uhlmann Oct. 26, 1943 2,335,180 Goldsmith Nov. 23, 1943 2,343,825 Wilson Mar. 7, 1944 2,422,778 Finch June 24, 1947 2,552,386 Sziklai May 8, 1951 FOREIGN PATENTS Number Country Date 451,959 Great Britain Aug. 14, 193,6 569,490 Great Britain Apr. 6, 1944 

